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Mon, 2 Nov 2026 14:26:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793629614; bh=9aVyOXB46BuISsBUhN38Gy53ksJP5B0VIb3fhsBGGRA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=kX8+D9NVfqUSc8gdnE5o7Q3Oq/uGaLH3xjedKLYih9wdsnnjGcjcRNyhrZaxgnxxx 6mJPp78Dyw5jmgqKUNdlhpYQ/2Qf2LxAvvtdrBxj50iBxD11Dxk7n+iHGOSy2yxUdF FBfa3aXoeS07kk/77nHtewMxpER9ltz8Mj/fE7xHULINbv3mdMS1KJ84n3AWWtBdk/ bya8kywSYeK0JZbU+HmtQD21/aGPUSusYBz+eyTQ4qL+4aq772xEp6pJWjXfU6i3HK oQcjHkwy6Nkk9N/kAx/z/L8sk7X6Lk8bFh4mVxNn8C/PKjrqbaPSzJA45GkFv8YnRt zK+G0svabDX1Q== From: Christian Brauner Date: Mon, 02 Nov 2026 15:21:37 +0100 Subject: [PATCH RFC 22/38] proc: warn about entries left in /proc/net of a dying namespace X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261102-work-procfs-bugfixes-v1-22-59422ed3e465@kernel.org> References: <20261102-work-procfs-bugfixes-v1-0-59422ed3e465@kernel.org> In-Reply-To: <20261102-work-procfs-bugfixes-v1-0-59422ed3e465@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1461; i=brauner@kernel.org; h=from:subject:message-id; bh=VO4WYvqdbdInF0wrRh04dkmiJiaJmigcn5WsH5ed6c4=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9mJO9wixVJYzvlj178KfJTowVe+L0g7o9JBeHSb4ui OJO1MvqKGVhEONikBVTZHFoNwmXW85TsdkoUwNmDisTyBAGLk4BmMiaf4wMS+2vzm0vtpws3xjx Ms/u6ofZgus/vnESzThVVPxXfJGuFSPDjsrTjR0fyxMDjG7OlZnMcnPhiY11+Y35btcVvI932r1 jBQA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 proc_net_ns_exit() runs after all the other pernet exits and frees net->proc_net right after removing "stat" from it. An entry that some pernet exit forgot to remove is left with a freed ->parent, and so PDE_NET() hands seq_open_net() and single_open_net() a freed struct net when the entry is opened through a file descriptor that someone kept. There is no such entry in the tree that we know of, but nothing would tell us about one either. So warn about it like remove_proc_entry() does for a directory that isn't empty. Reported-by: Chris Mason Fixes: e9720acd728a ("[NET]: Make /proc/net a symlink on /proc/self/net (v3)") Signed-off-by: Christian Brauner (Amutable) --- fs/proc/proc_net.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index dbcf87a257e1..df5484813d5d 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -410,7 +410,13 @@ static __net_init int proc_net_ns_init(struct net *net) static __net_exit void proc_net_ns_exit(struct net *net) { + struct proc_dir_entry *left; + remove_proc_entry("stat", net->proc_net); + /* Whatever is left still points at net->proc_net and so at net. */ + left = rb_entry_safe(rb_first(&net->proc_net->subdir), + struct proc_dir_entry, subdir_node); + WARN(left, "/proc/net: leaking at least '%s'\n", left->name); pde_free(net->proc_net); } -- 2.53.0